Organisms rely on large molecular machines that convert nucleic acids between their deoxyribose and ribose'forms to transmit genetic information. This proposal aims to study these molecular machines from the standpoint of human disease. In the case of HIV, reverse transcriptase (:RT) is responsible for catalyzing the transfer of information from viral genomic RNA to DMA. This series of reactions are crucial steps, and are absolutely required for viral replication. RT is a proven drug target, as evidenced by the number of therapeutics that function by inhibiting RT. Mutations to current drug binding sites on RT which confer resistance is the greatest cause of failure for chemotherapeutic intervention, compelling the development of novel drugs which can function in the face of these mutations. The ribonuclease H (RNH) domain of RT represents an underutilized drug target despite the required activity of the RH domain for proper RT function. Furthermore, the RNH domain is located away from current drug binding sites, reducing the risk of cross-resistance with current therapies. This study will execute a multi-tiered strategy to discover and develop novel inhibitors that target RT. First, fragment based screening in conjunction with x-ray crystallography will be used as a platform for screening chemical space for small molecule scaffolds that bind in the RNH active site and disrupt activity. Information derived from fragment screening will be exploited to develop novel RNH inhibitors that will eventually be turned into therapeutics to treat AIDS. Second, the structures of an existing class of N-acyl hydrazone inhibitors of RNH function in complex with RT will be determined using x-ray crystallography. Information gained from these structures will be used to elucidate the design of the next generation of more potent inhibitors. Finally, the interactions of the existing class of alkenyldiarylmethane (ADAM) inhibitors of RT polymerase activity will be determined using x-ray crystallography. Although effective polymerase inhibitors already exist, this structural information will aid in the development of ADAM analogues that can retain activity in the face of resistance mutations. [unreadable] [unreadable] PUBLIC HEALTH RELEVANCE: Novel molecules that inhibit the function of an absolutely required HIV enzyme will be discovered and developed via structural methods. These new inhibitors will contribute to combating the emergence of drug resistant strains of HIV. [unreadable] [unreadable] [unreadable]